Strong evidence exists that mechanical stress and hypoxia play an important role in the development of atherosclerosis. Patients with diabetes mellitus, who have a higher incidence of this disease, are subject to a number of metabolic derangements which may impair red cell deformability or blood oxygen delivery. Among these are elevations in free fatty acids, triglycerides, low and very low density lipoproteins and chylomicrons. The objective of this project is to search for correlations between elevated lipids and altered red cell function in diabetic patients representing various categories of insulin dependence, metabolic control, and other variables. Non-diabetic hyperlipidemic and atherosclerosis patients will also be studied, as well as a population of suitably matched healthy controls. Blood samples will be drawn both in the fasting state and following a standard high fat meal. Measurements will include red cell deformability by the micropipette technique, as well as by filtration and cone-plate viscometry; oxygen delivery by flowing blood in an in vitro model and factors which influence blood oxygen transport: and plasma and red cell lipid analyses. If this work demonstrates a relationship between abnormal lipid patterns and impaired red cell flexibility or blood oxygenation in the diabetic patient either in the fasting or postprandial state, it will not only stimulate further research into the role of mechanical stress of hypoxia in the generation of atherosclerosis but also will suggest that through dietary modification, diabetics, as well as other patients with certain hyperlipidemias, may well be able to delay the onset of this fatal complication.